In an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system, a User Equipment (UE) may perform a DRX operation, that is, turning off temporarily the receiver of the UE to save battery power of the UE, and waking up at the time predefined by the Node B to monitor a corresponding Physical layer Downlink Control Channel (PDCCH) so as to know whether there is data to be transmitted to the UE from the Node B. There are some parameters provided for the DRX operation, such as a DRX cycle and some control timers such as an on duration timer and a DRX inactivity timer. The DRX cycle includes a period of active time and a period of inactivity. The UE monitors the PDCCH in an on duration period, and if no downlink data transmission is indicated to the UE from the Node B, the UE enters into the period of inactivity after the expiration of the on duration timer; and if new downlink data transmission is indicated to the UE over the PDCCH during the on duration period, then the DRX inactivity timer starts, and if a period for which no new downlink data transmission is further indicated to the UE over the PDCCH lasts after the expiration of the DRX inactivity timer, then the UE enters into the inactivity status.
In the DRX operation, starting from monitoring the PDCCH in a DRX cycle, the receiver of the UE is turned on to enter into the active status. The E-UTRAN Node B (eNB) may transmit downlink data when the UE is monitoring the PDCCH. Due to the dynamic scheduling adopted in the E-UTRAN system, the Node B needs to know the status of downlink channel from a feedback of the UE, e.g. a CQI of the downlink channel, for downlink transmission. Periodical and non-periodical CQI report mechanisms are supported in the E-UTRAN system. The 3GPP has agreed on how to transmit CQI and SRS information in a DRX cycle for the E-UTRAN FDD system, that is, the CQI information could be transmitted from the UE in the active time of the DRX cycle. However, there is no agreed solution on the way to transmit the CQI and SRS information for the E-UTRAN TDD and HD-FDD systems.
In the TDD system, uplink and downlink transmissions are performed at the same frequency and staggered in time. In the HD-FDD system, uplink and downlink transmissions are performed respectively at different frequencies, but merely one of the uplink and downlink transmissions is performed at any time, which is similar to the TDD system.
In the existing E-UTRAN TDD system, there are seven modes of downlink and uplink sub-frame configuration in a radio frame as illustrated in FIG. 1, including:
a first configuration mode (Configuration 0): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 1DL:3UL with a periodicity of 5 ms, i.e., periodicity=5 ms;
a second configuration mode (Configuration 1): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 2DL:2UL with a periodicity of 5 ms, i.e., periodicity=5 ms;
a third configuration mode (Configuration 2): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 3DL:1UL with a periodicity of 5 ms, i.e., periodicity=5 ms;
a fourth configuration mode (Configuration 3): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 6DL:3UL with a periodicity of 10 ms, i.e., periodicity=10 ms;
a fifth configuration mode (Configuration 4): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 7DL:2UL with a periodicity of 10 ms, i.e., periodicity=10MS;
a sixth configuration mode (Configuration 5): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 8DL:1UL with a periodicity of 10 ms, i.e., periodicity=10 ms; and
a seventh configuration mode (Configuration 6): the proportion of downlink sub-frames (DL) to uplink sub-frames (UL) is 3DL:5UL with a periodicity of 10 ms, i.e., periodicity=10 ms.
In the prior art, the following two methods for reporting a CQI have been proposed for using the DRX operation in the TDD system.
In the first method, a CQI report is transmitted in the uplink sub-frame(s) in-between downlink sub-frames in the active time period. As illustrated in FIG. 2, it is assumed that there are five downlink sub-frames in the active time period, i.e., Active time=5, then a CQI is reported in the UL sub-frame in-between DL sub-frames in the active time period. In FIG. 2, the UL sub-frame to which a vertical and upward arrow without a cross mark points is the corresponding UL sub-frame used for reporting the CQI, and the UL sub-frame to which a vertical and upward arrow with a cross mark points is not intended for transmission of any CQI report.
In the second method, a CQI report is transmitted in each of uplink sub-frames of a radio frame(s) which the active time period spans, as illustrated in FIGS. 3 and 4. In FIG. 3, the active time period is in the nth radio frame, and then a CQI report is transmitted in each of uplink sub-frames of the nth radio frame (four UL sub-frames are denoted in FIG. 3). In FIG. 4, the active time period spans the nth and (n+1)th radio frames, and then a CQI report is transmitted in each of uplink sub-frames of the nth radio frame (four UL sub-frames are denoted in FIG. 4) and of uplink sub-frames of the (n+1)th radio frame (four UL sub-frames are denoted in FIG. 4).
The above two methods in the prior art present their own disadvantages.
In the first method, inclusion of an uplink sub-frame in the active time period can not be ensured, and consequently it is possible that no CQI report can be transmitted at all.
In the second method, on one hand, it might be possible that a CQI report is transmitted in an uplink when the active time period ends and the receiver of the UE has reentered into the inactivity status. However, since no downlink transmission has been indicated at this time, the subsequently transmitted CQI is useless, and transmission of the CQI in this case is a waste of uplink resources; and on the other hand, in order to know uplink sub-frames available for transmission of a CQI, an upper layer allocating transmission resources for the CQI has to know the number and boundaries of radio frames which the active time period spans, which also increases the complexity and uncertainty.